Fix for negative temp in Eddystone TLM; solving #7618 (#7791)

* Changed data type of temperature

* Changed data type in EddystoneTLM class and example

* Revert "Changed data type in EddystoneTLM class and example"

This reverts commit 1f3a9414ee13341f80bd6d51cdbd57254aadfe97.

* Draft of Eddystone TLM example

* Adds MACROs to convert beacon temperature 

2 Macros
EDDYSTONE_TEMP_U16_TO_FLOAT(tempU16)  - takes the TLM BigEndian 8.8 fixed point representation and returns its float value 
EDDYSTONE_TEMP_FLOAT_TO_U16(tempFloat)  - takes a float (temperature) and returns its BigEndian 8.8 fixed point representation

* Fixed temp

* Changed to conform with PR comments

* Fixed comment on closing bracket

* Prints negative TEMP big endian as just 2 bytes

* Extacts correct Eddyston Service Data

* Fixes BLEEddystoneTLM::toString() negative temp

* Fixes URL field length

* Fixes Eddystone URL decoding

* Fixes MSB for iBeacon UUID

iBeacons use big endian BLE fields.

* Fix to detect iBeacon that also has Service UUID

This fix makes the BLE_iBeacon.ino to work correctly with the BLE_Beacon_Scanner.ino example

---------
Co-authored-by: NRodrigo Garcia <rodrigo.garcia@espressif.com>

libraries/BLE/examples/BLE_Beacon_Scanner/BLE_Beacon_Scanner.ino

@@ -14,8 +14,6 @@
 #include <BLEEddystoneTLM.h>
 #include <BLEBeacon.h>
 
-#define ENDIAN_CHANGE_U16(x) ((((x)&0xFF00) >> 8) + (((x)&0xFF) << 8))
-
 int scanTime = 5; //In seconds
 BLEScan *pBLEScan;
 
@@ -37,8 +35,7 @@ class MyAdvertisedDeviceCallbacks : public BLEAdvertisedDeviceCallbacks
         Serial.println(devUUID.toString().c_str());
         Serial.println("");
       }
-      else
-      {
+      
       if (advertisedDevice.haveManufacturerData() == true)
       {
         std::string strManufacturerData = advertisedDevice.getManufacturerData();
@@ -65,30 +62,39 @@ class MyAdvertisedDeviceCallbacks : public BLEAdvertisedDeviceCallbacks
           Serial.printf("\n");
         }
       }
-        return;
-      }
 
       uint8_t *payLoad = advertisedDevice.getPayload();
+      // search for Eddystone Service Data in the advertising payload
+      // *payload shall point to eddystone data or to its end when not found
+      const uint8_t serviceDataEddystone[3] = {0x16, 0xAA, 0xFE}; // it has Eddystone BLE UUID
+      const size_t payLoadLen = advertisedDevice.getPayloadLength();
+      uint8_t *payLoadEnd = payLoad + payLoadLen - 1; // address of the end of payLoad space
+      while (payLoad < payLoadEnd) {
+        if (payLoad[1] == serviceDataEddystone[0] && payLoad[2] == serviceDataEddystone[1] && payLoad[3] == serviceDataEddystone[2]) {
+          // found!
+          payLoad += 4;
+          break;
+        }
+        payLoad += *payLoad + 1;  // payLoad[0] has the field Length
+      }
 
-      BLEUUID checkUrlUUID = (uint16_t)0xfeaa;
-
-      if (advertisedDevice.getServiceUUID().equals(checkUrlUUID))
+      if (payLoad < payLoadEnd) // Eddystone Service Data and respective BLE UUID were found
       {
-        if (payLoad[11] == 0x10)
+        if (*payLoad == 0x10)
         {
           Serial.println("Found an EddystoneURL beacon!");
           BLEEddystoneURL foundEddyURL = BLEEddystoneURL();
-          std::string eddyContent((char *)&payLoad[11]); // incomplete EddystoneURL struct!
-
-          foundEddyURL.setData(eddyContent);
+          uint8_t URLLen = *(payLoad - 4) - 3;  // Get Field Length less 3 bytes (type and UUID) 
+          foundEddyURL.setData(std::string((char*)payLoad, URLLen));
           std::string bareURL = foundEddyURL.getURL();
           if (bareURL[0] == 0x00)
           {
-            size_t payLoadLen = advertisedDevice.getPayloadLength();
+            // dumps all bytes in advertising payload
             Serial.println("DATA-->");
+            uint8_t *payLoad = advertisedDevice.getPayload();
             for (int idx = 0; idx < payLoadLen; idx++)
             {
-              Serial.printf("0x%08X ", payLoad[idx]);
+              Serial.printf("0x%02X ", payLoad[idx]);
             }
             Serial.println("\nInvalid Data");
             return;
@@ -99,29 +105,18 @@ class MyAdvertisedDeviceCallbacks : public BLEAdvertisedDeviceCallbacks
           Serial.printf("TX power %d\n", foundEddyURL.getPower());
           Serial.println("\n");
         } 
-        else if (payLoad[11] == 0x20)
+        else if (*payLoad == 0x20)
         {
           Serial.println("Found an EddystoneTLM beacon!");
-          BLEEddystoneTLM foundEddyURL = BLEEddystoneTLM();
-          std::string eddyContent((char *)&payLoad[11]); // incomplete EddystoneURL struct!
-
-          eddyContent = "01234567890123";
-
-          for (int idx = 0; idx < 14; idx++)
-          {
-            eddyContent[idx] = payLoad[idx + 11];
-          }
  
-          foundEddyURL.setData(eddyContent);
-          Serial.printf("Reported battery voltage: %dmV\n", foundEddyURL.getVolt());
-          Serial.printf("Reported temperature from TLM class: %.2fC\n", (double)foundEddyURL.getTemp());
-          int temp = (int)payLoad[16] + (int)(payLoad[15] << 8);
-          float calcTemp = temp / 256.0f;
-          Serial.printf("Reported temperature from data: %.2fC\n", calcTemp);
-          Serial.printf("Reported advertise count: %d\n", foundEddyURL.getCount());
-          Serial.printf("Reported time since last reboot: %ds\n", foundEddyURL.getTime());
+          BLEEddystoneTLM eddystoneTLM;
+          eddystoneTLM.setData(std::string((char*)payLoad, 14));
+          Serial.printf("Reported battery voltage: %dmV\n", eddystoneTLM.getVolt());
+          Serial.printf("Reported temperature: %.2f°C (raw data=0x%04X)\n", eddystoneTLM.getTemp(), eddystoneTLM.getRawTemp());
+          Serial.printf("Reported advertise count: %d\n", eddystoneTLM.getCount());
+          Serial.printf("Reported time since last reboot: %ds\n", eddystoneTLM.getTime());
           Serial.println("\n");
-          Serial.print(foundEddyURL.toString().c_str());
+          Serial.print(eddystoneTLM.toString().c_str());
           Serial.println("\n");
         }
       }

libraries/BLE/examples/BLE_EddystoneTLM_Beacon/BLE_EddystoneTLM_Beacon.ino

@@ -13,6 +13,7 @@
    5. Stop advertising.
    6. deep sleep
    
+   To read data advertised by this beacon use second ESP with example sketch BLE_Beacon_Scanner
 */
 #include "sys/time.h"
 
@@ -22,7 +23,7 @@
 #include "BLEUtils.h"
 #include "BLEBeacon.h"
 #include "BLEAdvertising.h"
-#include "BLEEddystoneURL.h"
+#include "BLEEddystoneTLM.h"
 
 #include "esp_sleep.h"
 
@@ -48,10 +49,10 @@ void setBeacon()
   char beacon_data[25];
   uint16_t beconUUID = 0xFEAA;
   uint16_t volt = random(2800, 3700); // 3300mV = 3.3V
-  float tempFloat = random(2000, 3100) / 100.0f;
-  Serial.printf("Random temperature is %.2fC\n", tempFloat);
-  int temp = (int)(tempFloat * 256); //(uint16_t)((float)23.00);
-  Serial.printf("Converted to 8.8 format %0X%0X\n", (temp >> 8), (temp & 0xFF));
+  float tempFloat = random(-3000, 3000) / 100.0f;
+  Serial.printf("Random temperature is %.2f°C\n", tempFloat);
+  int temp = (int)(tempFloat * 256);
+  Serial.printf("Converted to 8.8 format %0X%0X\n", (temp >> 8) & 0xFF, (temp & 0xFF)); 
 
   BLEAdvertisementData oAdvertisementData = BLEAdvertisementData();
   BLEAdvertisementData oScanResponseData = BLEAdvertisementData();
@@ -82,13 +83,11 @@ void setBeacon()
 
 void setup()
 {
-
   Serial.begin(115200);
   gettimeofday(&nowTimeStruct, NULL);
 
-  Serial.printf("start ESP32 %d\n", bootcount++);
-
-  Serial.printf("deep sleep (%lds since last reset, %lds since last boot)\n", nowTimeStruct.tv_sec, nowTimeStruct.tv_sec - last);
+  Serial.printf("Starting ESP32. Bootcount = %d\n", bootcount++);
+  Serial.printf("Deep sleep (%lds since last reset, %lds since last boot)\n", nowTimeStruct.tv_sec, nowTimeStruct.tv_sec - last);
 
   last = nowTimeStruct.tv_sec;
   lastTenth = nowTimeStruct.tv_sec * 10; // Time since last reset as 0.1 second resolution counter
@@ -103,12 +102,11 @@ void setup()
   setBeacon();
   // Start advertising
   pAdvertising->start();
-  Serial.println("Advertizing started for 10s ...");
+  Serial.println("Advertising started for 10s ...");
   delay(10000);
   pAdvertising->stop();
-  Serial.printf("enter deep sleep for 10s\n");
+  Serial.printf("Enter deep sleep for 10s\n");
   esp_deep_sleep(1000000LL * GPIO_DEEP_SLEEP_DURATION);
-  Serial.printf("in deep sleep\n");
 }
 
 void loop()

libraries/BLE/src/BLEBeacon.cpp

@@ -40,7 +40,7 @@ uint16_t BLEBeacon::getMinor() {
 }
 
 BLEUUID BLEBeacon::getProximityUUID() {
-	return BLEUUID(m_beaconData.proximityUUID, 16, false);
+	return BLEUUID(m_beaconData.proximityUUID, 16, true);
 }
 
 int8_t BLEBeacon::getSignalPower() {

libraries/BLE/src/BLEEddystoneTLM.cpp

@@ -17,8 +17,6 @@
 #include "BLEEddystoneTLM.h"
 
 static const char LOG_TAG[] = "BLEEddystoneTLM";
-#define ENDIAN_CHANGE_U16(x) ((((x)&0xFF00)>>8) + (((x)&0xFF)<<8))
-#define ENDIAN_CHANGE_U32(x) ((((x)&0xFF000000)>>24) + (((x)&0x00FF0000)>>8)) + ((((x)&0xFF00)<<8) + (((x)&0xFF)<<24))
 
 BLEEddystoneTLM::BLEEddystoneTLM() {
 	beaconUUID = 0xFEAA;
@@ -47,9 +45,13 @@ uint16_t BLEEddystoneTLM::getVolt() {
 } // getVolt
 
 float BLEEddystoneTLM::getTemp() {
-	return ENDIAN_CHANGE_U16(m_eddystoneData.temp) / 256.0f;
+  return EDDYSTONE_TEMP_U16_TO_FLOAT(m_eddystoneData.temp);
 } // getTemp
 
+uint16_t BLEEddystoneTLM::getRawTemp() {
+	return ENDIAN_CHANGE_U16(m_eddystoneData.temp);
+} // getRawTemp
+
 uint32_t BLEEddystoneTLM::getCount() {
 	return ENDIAN_CHANGE_U32(m_eddystoneData.advCount);
 } // getCount
@@ -73,7 +75,7 @@ std::string BLEEddystoneTLM::toString() {
   out += " mV\n";
 
   out += "Temperature ";
-  snprintf(val, sizeof(val), "%.2f", ENDIAN_CHANGE_U16(m_eddystoneData.temp) / 256.0f);
+  snprintf(val, sizeof(val), "%.2f", ((int16_t)ENDIAN_CHANGE_U16(m_eddystoneData.temp)) / 256.0f);
   out += val;
   out += " C\n";
 
@@ -110,6 +112,21 @@ std::string BLEEddystoneTLM::toString() {
 
 /**
  * Set the raw data for the beacon record.
+ * Example:
+ * uint8_t *payLoad = advertisedDevice.getPayload();
+ * eddystoneTLM.setData(std::string((char*)payLoad+22, advertisedDevice.getPayloadLength() - 22));
+ * Note: the offset 22 works for current implementation of example BLE_EddystoneTLM Beacon.ino, however it is not static and will be reimplemented
+ * Data frame:
+ * | Field  || Len | Type | UUID        | EddyStone TLM |
+ * | Offset || 0   | 1    | 2           | 4             |
+ * | Len    || 1 B | 1 B  | 2 B         | 14 B          |
+ * | Data   || ??  | ??   | 0xAA | 0xFE | ???           |
+ *
+ * EddyStone TLM frame:
+ * | Field  || Type  | Version | Batt mV     | Beacon temp | Cnt since boot | Time since boot |
+ * | Offset || 0     | 1       | 2           | 4           | 6              | 10              |
+ * | Len    || 1 B   | 1 B     | 2 B         | 2 B         | 4 B            | 4 B             |
+ * | Data   || 0x20  | ??      | ??   | ??   | ??    | ??  |   |   |   |    |   |   |   |     |
  */
 void BLEEddystoneTLM::setData(std::string data) {
 	if (data.length() != sizeof(m_eddystoneData)) {
@@ -132,7 +149,7 @@ void BLEEddystoneTLM::setVolt(uint16_t volt) {
 } // setVolt
 
 void BLEEddystoneTLM::setTemp(float temp) {
-	m_eddystoneData.temp = (uint16_t)temp;
+	m_eddystoneData.temp = EDDYSTONE_TEMP_FLOAT_TO_U16(temp);
 } // setTemp
 
 void BLEEddystoneTLM::setCount(uint32_t advCount) {

libraries/BLE/src/BLEEddystoneTLM.h

@@ -10,6 +10,10 @@
 #include "BLEUUID.h"
 
 #define EDDYSTONE_TLM_FRAME_TYPE 0x20
+#define ENDIAN_CHANGE_U16(x) ((((x)&0xFF00)>>8) + (((x)&0xFF)<<8))
+#define ENDIAN_CHANGE_U32(x) ((((x)&0xFF000000)>>24) + (((x)&0x00FF0000)>>8)) + ((((x)&0xFF00)<<8) + (((x)&0xFF)<<24))
+#define EDDYSTONE_TEMP_U16_TO_FLOAT(tempU16)   (((int16_t)ENDIAN_CHANGE_U16(tempU16)) / 256.0f)
+#define EDDYSTONE_TEMP_FLOAT_TO_U16(tempFloat) (ENDIAN_CHANGE_U16(((int)((tempFloat) * 256))))
 
 /**
  * @brief Representation of a beacon.
@@ -24,6 +28,7 @@ public:
   uint8_t   getVersion();
   uint16_t  getVolt();
   float     getTemp();
+  uint16_t  getRawTemp();
   uint32_t  getCount();
   uint32_t  getTime();
   std::string toString();

libraries/BLE/src/BLEEddystoneURL.h

@@ -35,7 +35,7 @@ private:
 	struct {
 		uint8_t frameType;
 		int8_t  advertisedTxPower;
-		uint8_t url[16];
+		uint8_t url[18];  // 18 bytes: 1 byte for URL scheme + up to 17 bytes of URL
 	} __attribute__((packed)) m_eddystoneData;
 
 }; // BLEEddystoneURL